This invention relates to fixed and movable frame fixtures for doors and windows.
The instant fixtures are useful in all those applications wherein the conventional fixture are used, such as one- or two-wing doors or windows, bottom hung or jutting windows, horizontal and vertical center hung windows and doors, as well as fixed pane windows and curtain walls in general.
Modern building techniques have developed in this field a distinct trend towards metal frame fixtures, particularly towards frames formed from aluminium sections, owing to the ease of insertion of such sections in the bearing structures, their quick assembling features in the field, and the high degree of accuracy obtainable therewith, which eliminates in practice the need of carrying out adjustments during the installation. Their competitive cost and ease of transportation, for example with respect to the concrete prefabricated window bays, have also contributed to the widespread acceptance of metal frame fixtures. Specific problems connected with some special window designs, have also been conveniently solved thanks to the section adaptability to suit a variety of different requirements.
However, the very presence of a metal, which is advantageous for many aspects, brings about an inconvenience that in some cases may develop into a serious problem. Such an inconvenience results from the high thermal conductivity of metals in general, which for aluminium reaches values very close to the known maxima. In very cold climates and seasons, the thermal conductivity of the fixture frames around doors and windows creates within the house cold wall areas, as the sections extend, cross-section-wise, continuously from the outer surface to the inner one of a wall. Still more inconvenient than the loss of heat through this path, which may be limited owing to the small surface exposed and low rate of exchange between air and metal, is the presence of cold spots in a heated room, since these act as condensation centers even when the room relative humidity is very low. It is a generally recognized fact that condensation within a room is to be prevented as far as possible.